One cause of accidents between motor vehicles is the inability of motorists to communicate with each other in a fast, safe, efficient manner. The importance of communication between motorists is underscored by the requirement that a vehicle have appropriate communication signals before it can be licensed for use on public roads. These signals include standardized methods of communicating actions such as turning, stopping, and reversing. Additional communication means are especially desirable for larger vehicles, such as trucks, which require more space to stop and turn than other motorists may anticipate, and which obstruct the view of the motorists behind the truck.
One method of communicating messages, in addition to the standard signals typically found on trucks, is a display unit on which the motorist, or a passenger, can present a message. Some of these devices can present an unlimited number of messages, and others present only a predetermined selection of messages. Those devices which can present an unlimited number of messages require an input device, such as a keyboard, on which the message is entered. Entry of a subsequent command presents the message on the display unit. Those devices which present a predetermined selection of messages typically provide an input device such as a switch with several positions, or a keypad with several keys, where each switch position or key corresponds to one of the predetermined messages. The selected message is presented by setting the switch to the desired position, or pressing the desired key.
Selecting the message to be presented on such devices diverts the motorist's attention from the road, and therefore the use of these devices may create a safety risk. For example, to use an input device such as a keypad, the motorist typically looks away from the road to find the appropriate key on the pad. Even in the case of the switch with several positions, which might be easily found by touch without looking away from the road, selection of the appropriate switch setting requires the motorist to divert attention from driving. Using a keyboard to type and enter a message for presentation typically requires an even greater amount of the motorist's attention.
What is needed, therefore, is a display unit for presenting messages from a motor vehicle, the use of which does not require the motorist to look away from the road, or require a significant amount of the motorist's attention in the selection of the message to be presented.